Bearings – Rotary bearing – Antifriction bearing
Patent
1999-08-04
2000-10-17
Footland, Lenard A.
Bearings
Rotary bearing
Antifriction bearing
F16C 3358
Patent
active
061320978
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a roller bearing of the type incorporating an outer and an inner race ring having confronting race tracks and a number of rollers being interposed between and in contact with said race tracks, said rollers and race tracks having longitudinal section profiles of a radius of curvature which is bigger than the distance between the outer race track and the axis of the bearing, as measured perpendicularly to the race track, which rollers thereby are axially movable across the race tracks without being hindred by axial limitations at the race tracks, in order to allow relative misalignment and axial displaceability of the race tracks and it refers to such a roller bearing having means for giving the rollers a positive skew angle, when axially displaced.
Bearing of this type are known e.g. from EP-B1-0175858 and EP-B1-0520968, and they combine different advantages from other types of bearings, such as axial mobility as a cylindrical roller bearing, self alignment as a spherical roller bearing and low section height as a needle roller bearing.
The present type of bearing has the ability of allowing axial displacement between the rollers and the race rings and also between the two race rings, and it also permits high degrees of misalignment. When the rings of such a bearing are displaced axially, the contact angle resulting therefrom is small. Particularly when the internal clearance of the bearing is small, or when the bearing is pre-loaded, it is essential that the skew rolling angle, if any, is positive or zero, as otherwise there can be a tendency that the race rings are pulled in over each other, thereby risking that the rollers are being jammed between the race tracks, if the axial guidance of the shaft from other bearings is poor or absent.
The skew angle is defined as positive when the axial friction forces from the roller on the race ways arising as a result of roller skew, have the same axial direction as the axial component of the normal load from the roller on the raceway.
A positive skew angle gives the bearing capability of taking up more thrust, whereas a negative skew angle reduces this capability and even might damage the bearing. In rolling bearings it is often desirable to control that the bearing has a positive skew angle in order to ascertain that the friction forces emanating from the contact between the roller and its adjoining race tracks cooperate with the friction forces at normal rolling for giving the rolling bodies a minimum of friction under load, and this is often achieved by giving the race track surfaces, i.e., the surfaces of the race rings against which the roller normally rolls, certain surface patterns.
In a bearing of the type now concerned, it however is possible to obtain roller skew control, e.g. for avoiding the above mentioned tendencies that the race rings are pulled in over each other, also in other manners, and this is achieved in accordance with the characterizing part.
BRIEF DESCRIPTION OF THE FIGURES
Hereinafter the invention will be further described by way of an embodiment schematically shown in the accompanying drawing.
FIG. 1 shows a section through a roller bearing of the type concerned in a neutral position,
FIG. 2 is a view corresponding to FIG. 1, but with the bearing rings and the rollers in axially displaced positions.
FIG. 1 of the drawing shows a section through a portion (half) of a bearing of the type referred to and incorporating an outer race ring 1 having at its inner envelope surface a first race track 2, and an inner race ring 3, having at its outer envelope surface a second race track 4. These two race tracks 2, 4 define between them an annular space occupied by a number of rollers 5. The race rings 1, 3 are shown in cross section, although they are not hatched in order to increase the clearness of the presentation.
The rollers 5 and the race tracks 2, 4 of the bearing of this type have essentially the same radius of curvature R, and this radius of curvature is bigger than the geometrical radius of the bearing i
REFERENCES:
patent: 3990753 (1976-11-01), Kellstrom et al.
patent: 5586826 (1996-12-01), Kellstrom et al.
Footland Lenard A.
SKF Aktiebolaget
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